Housing for an equipment rack

ABSTRACT

The present invention provides a housing for holding a rack of equipment (210), comprising a main enclosure portion (200) for retaining the rack (210), the main enclosure portion (200) having a first opening for receiving the rack (210) and comprising a first wall (310) defining at least one edge of said first opening. A wiring portion (205), distinct from said main enclosure portion (200), is also provided for receiving wires (220) to be routed to said rack (210), and the first wall (310) is arranged to separate the wiring portion (205) from said main enclosure portion (200), such that the wiring portion (205) is located between the first wall (310) and a front face of the housing. Due to the proximity of the wiring portion (205) to the front face of the housing, this arrangement significantly improves access to the wiring of the housing, thereby reducing the time taken to install and commission a system, and to perform routine checks on the wiring.

TECHNICAL FIELD OF THE INVENTION

The present invention relates generally to housings used to hold itemsof equipment, and in particular to a housing for holding an equipmentrack.

BACKGROUND OF THE INVENTION

Housings developed for holding racks of equipment generally take theform of a tower of substantially rectangular cross-section. A number ofStandards have been established over the years to define certainfeatures of these housings, so that racks of equipment can then bedesigned to be held in any housing that meets a defined "Standard". Onesuch Standard is the European Telecommunications Standards Institute(ETSI) Standard, which defines the cross-sectional dimensions of therack, often referred to as the "footprint", the spacing of the mountingholes, etc.

A typical prior art housing is illustrated in FIGS. 1A and 1B. FIG. 1Aillustrates a plan view of a typical prior art housing, whilst FIG. 1Billustrates a perspective view. As illustrated in FIG. 1A, a back wall100 has two internal side walls 120 depending therefrom. Each internalside wall 120 is bent at its far end to form a U-shaped end portion 130,which provides the side wall 120 with increased structural rigidity.

External detachable side walls 150 are provided, which may be attachedto the back wall 100 of the housing. Further, a front cover 160 may beattached to the front of the housing if desired. This front cover 160may take the form of a detachable panel, or alternatively may beprovided as a hinged door attached to the housing.

With the front cover removed, or hinged open, a rack of equipment may beinserted into the housing, and attached by a suitable fasteningmechanism, for example a number of bolts, to the front faces 140 of theinternal side walls 120. Due to the U-shaped sections 130 provided inthe side walls 120, these side walls 120 have sufficient mechanicalrigidity to retain one or more racks of equipment.

As illustrated in FIG. 1B, wiring that needs to be routed to a rack ofequipment may be threaded down the gaps 170 between the internal sidewalls 120 and the external side walls 150, and may then be passedthrough appropriate openings 190 in the side walls 120 in order thatthey can be connected to the racks.

As is apparent from FIGS. 1A and 1B, one problem with such a prior artarrangement is that the front access to the spaces 170 containing thewiring is through a rather restricted narrow entrance 180, this narrowentrance being formed as a direct result of the U-shaped channels 130introduced to improve mechanical rigidity. This can impede maintenancework, and/or the introduction of new wiring into the housing,particularly if a number of similar housings are located side by side,so that there is no longer the possibility of removing the side walls150 in order to obtain side access to these wiring areas. SinceStandards such as the ETSI Standard will dictate the overall dimension"X" illustrated in FIG. 1A, it is not possible merely to increase thewidth of the housing, in order to improve the front access to the wiringthrough the opening 180.

Hence, it is an object of the present invention to provide a housing forholding a rack of equipment, which provides improved access to thewiring routed within such a housing.

SUMMARY OF THE INVENTION

Viewed from a first aspect, the present invention provides a housing forholding a rack of equipment, comprising: a main enclosure portion forretaining the rack, the main enclosure portion having a first openingfor receiving the rack and comprising a first wall defining at least oneedge of said first opening; a wiring portion, distinct from said mainenclosure portion, for receiving wires to be routed to said rack; thefirst wall being arranged to separate the wiring portion from said mainenclosure portion, and the wiring portion being located between thefirst wall and a front face of the housing.

In accordance with the present invention, a first wall of the mainenclosure portion is used to separate the wiring portion from the mainenclosure portion, and the wiring portion is positioned forward of thefirst opening in the main enclosure portion, between the first wall anda front face of the housing. Due to the proximity of the wiring portionto the front face of the housing, this arrangement significantlyimproves access to the wiring of the housing, thereby reducing the timetaken to install and commission a system, and to perform routine checkson the wiring.

In preferred embodiments, the wiring portion has a second opening forinserting said wires in to the wiring portion, the first opening andsecond opening being accessible from the front face of the housing. Thisarrangement is particularly preferable, since racks can be readilyinserted and removed, and the necessary wiring then readily connectedto, or disconnected from, those racks, via the front access to both themain enclosure portion and the wiring portion.

Preferably, the wires are routed through said first wall to said rack.In preferred embodiments, each said wire consists of two separate wires,the first wire being located within the wiring portion, the second wirebeing located within the main enclosure portion, and the first andsecond wires being electrically connected to each other by a bulkheadconnector attached to the first wall. When connected to the bulkheadconnector, the first and second wires form a single electrical path forthe transmission of signals to the rack. Further, if the first wall ismade of a conductive material, the bulkhead connector ensures that agood electrical contact is made with the conductive wall, and that hencean outer portion of both the first and second wires are earthed againstthe conductive wall. This effectively inhibits the transmission of noisealong the wires to the rack.

In preferred embodiments, a part of the first wall comprises a mountingplate formed on the rack, and the bulkhead connector is attached to saidmounting plate. This approach enables the bulkhead connector to befitted, and the second wire to then be connected between the bulkheadconnector and the rack, prior to the rack being positioned within thehousing. When the mounting plate is mounted on the first wall, all thatis then required is for the first wire to be connected directly to thebulkhead connector with the rack "in situ". This approach hence furthereases installation of the rack.

Preferably, the wiring portion is connected to said first wall. Inpreferred embodiments, a back wall of said wiring portion is providedadjacent said first wall, and a first side wall of the wiring portiondepends from the main enclosure portion. This first side wall may beformed from a unitary piece of material also forming part of the mainenclosure portion, or alternatively may be entirely separate from themain enclosure portion. In preferred embodiments, this first side wallof the wiring portion is formed from a piece of metal having anincreased mechanical strength over the material used to form the wallsof the main enclosure portion, and hence this first side wall of thewiring portion, when connected to the main enclosure portion, increasesthe mechanical strength of the housing.

In preferred embodiments, a second side wall of the wiring portion isformed by an edge of the rack. Further, in areas of the housing notoccupied by a rack, the second side wall is preferably formed by an edgeof a blank insert that is inserted into those areas.

In preferred embodiments, the housing further comprises a plurality ofwalls arranged to define said main enclosure portion, at least two ofsaid walls being formed from a single piece of conductive material. Ithas been found that any gaps between the outer walls of said mainenclosure portion may act as slot antennae which propagate noise fromthe housing, and hence can cause the housing to not meet emissionrequirements. This effect is even more noticeable if any of the sidewalls are not properly earthed. Hence, by ensuring that at least two ofthe side walls are formed from a single piece of conductive material,the gap that would otherwise exist between those two walls is removed,and hence the emissions from the housing are reduced. In preferredembodiments, the plurality of walls are formed from a single piece ofconductive material, thereby further reducing the emissions that mayotherwise have been caused by gaps between the walls.

Preferably, a cover is provided for said second opening, which isattachable to the wiring portion. This protects the wires from damageduring use, but is readily removable in order to obtain access to thewiring portion.

Viewed from a second aspect, the present invention provides a centralterminal for a wireless telecommunications system, comprising a housingin accordance with the first aspect of the present invention, and anumber of racks of equipment retained in the housing.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described further, by way of example only,with reference to a preferred embodiment thereof as illustrated in theaccompanying drawings, in which:

FIGS. 1A and 1B illustrate a typical prior art housing used forretaining one or more racks of equipment;

FIG. 2 illustrates a plan view of a housing in accordance with preferredembodiments of the present invention;

FIG. 3 provides an enlarged view of a portion of the housing illustratedin FIG. 2;

FIG. 4 illustrates an enlarged view of a portion of the housingillustrated in FIG. 2, in which a removable cover is connected to thewiring portion; and

FIG. 5 illustrates a central terminal of a wireless telecommunicationssystem which uses a housing in accordance with preferred embodiments ofthe present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 2 illustrates a housing for an equipment rack, in accordance withpreferred embodiments of the present invention. As illustrated in FIG.2, the main enclosure portion 200 of the housing is formed from aunitary sheet of conductive material, for example sheet steel.

It has been found that any gaps between the outer walls of said mainenclosure portion can act as slot antennae which propagate noise fromthe housing, and hence can cause the housing to not meet emissionrequirements. Often, the walls of the main enclosure are painted, andhence even if the walls do abut each other, the thin layer of paint willact as an insulating layer between the two walls, and hence have thesame effect as an actual gap.

Hence, by forming all of the side walls of the main enclosure portionfrom a single sheet of conductive material, such as a sheet of metal,the gaps that would otherwise exist between the walls are removed, andhence the emissions from the housing are reduced.

When a rack of equipment 210 is inserted into the housing, it is, inaccordance with preferred embodiments of the present invention, fastenedto the walls 310 of the main enclosure portion 200 via suitablefastening devices, such as screws and cage nuts 245, mounting plates 240being provided on each side of the rack for receiving the screws.

In preferred embodiments, the mounting plates 240 are also made of aconductive material, preferably steel, and hence an electricallyconductive path is formed from the mounting plates 240 to the walls ofthe main enclosure portion 200 via the screws and cage nuts 245.

Also attached to the front face of the main enclosure portion are twoU-shaped sheets 250, these preferably being mounted onto the front walls310 of the main enclosure portion 200 via the screws and cage nuts 245and by rivets 280. Preferably, these sheets 250 are made of metal of athickness somewhat greater than that of the walls of the main enclosureportion 200. Once these sheets 250 are attached to the front face 310 ofthe main enclosure portion 200, they serve to increase the structuralrigidity of the housing. Further, these sheets 250 serve to define awiring portion 205 in which wires destined for the rack may be routed.

As illustrated in FIG. 2, and shown in more detail in FIGS. 3 and 4, onesuch wire 220 is drawn within the wiring portion 205. In preferredembodiments, these wires are coaxial cables, having a central metalliccore along which the signal passes, and a metallic shielding layerdisplaced radially outwardly from the central core for shielding thecentral core from external noise such as electromagnetic emissions fromother equipment in the vicinity.

At one end of the coaxial cable 220, a connector 235 is attached, thisconnector being arranged to be inserted into a bulkhead connector 230provided on the mounting plate 240 of the rack 210.

It will be appreciated by those skilled in the art that, since themounting plate 240, the sheet 250, and the walls 200 of the mainenclosure portion, are preferably all made of electrically conductivematerial, then the bulkhead connector 230 may be provided at anysuitable position between the wiring portion 205 and the main enclosureportion 200 to enable the cable 220 to be routed into the main enclosureportion 200. However, in preferred embodiments, the bulkhead connector230 is provided on the mounting plate 240, since this enables the rack210 to be assembled prior to installation in the housing, with a furtherportion of coaxial cable 225 extending from the bulkhead connector 230to a point of connection 300 on the rack 210. As illustrated in FIG. 2,the point of connection 300 may be a backplane of the rack, and asuitable connector can be provided so as to allow the connector 290attached to the end of the coaxial cable 225 to be connected to thebackplane 300.

By employing this arrangement, all that is required by the installationengineer is to install the rack 210 within the main enclosure portion200 by fastening the mounting plates 240 to the walls 310 with thescrews and cage nuts 245, and then to connect the connector 235 of thecoaxial cable 220 to the bulkhead connector 230.

The coaxial cable 220 may be of a significant length, typicallyextending over a substantial length of the housing from top to bottom,and such cables are prone to propagate any external emissions as noisealong the shielding layer of the coaxial cable 220. However, since theshielding layer of the coaxial cable 220 is connected via the bulkheadconnector 230 to the mounting plate 240, and hence to the walls of themain enclosure portion 200, then any signal being transmitted along thisouter shielding layer as noise is earthed against the conductive wallsof the main enclosure portion, and hence is not propagated along thecoaxial cable 225 to the point of connection 300 with the rack 210.Hence, the arrangement illustrated in FIGS. 2 to 4 provides a simple yeteffective mechanism for removing any noise propagated along the coaxialcable 220 before the cable enters the main enclosure portion and isrouted to the rack 210.

As illustrated in FIGS. 2 and 4, a cover 260 may be attached via afastening device 270, such as a quick release fastener, to the sheet 250defining the wiring portion 205, this cover enabling the wires withinthe wiring portion to be enclosed during normal use so as to reduce thelikelihood of any damage to the wires. Further, the cover 260 can bereadily removed to allow easy access to the wiring portion 205 from thefront face of the housing.

Hence, in accordance with the housing structure of preferred embodimentsas illustrated in FIGS. 2 to 4, the opening of the main enclosureportion 200 through which the rack 210 is inserted into the mainenclosure portion, and the opening in the wiring portion through-whichthe wires can be inserted into the wiring portion, both are accessibledirectly from the front face of the housing, this significantlysimplifying the installation process. This ease of access to the wiringportions is obtained whilst still ensuring that the overall housingmeets the "footprint" requirements of Standards such as the ETSIStandard. In accordance with preferred embodiments of the presentinvention, the wiring portions are located between the walls 310 formingpart of the main enclosure portion 200 and the front face of thehousing.

A further aspect of the design which eases the installation of racksinto the housing is the use of the bulkhead connector 230, which avoidsthe requirement to attach Ferrites to the cables in order to removenoise being transmitted along them. Further, if the bulkhead connector230 is provided within the mounting plate 240 of the rack 210, the useof such a bulkhead connector enables the wiring of the rack containedwithin the main enclosure portion 200 to be completed prior to theactual installation of the rack 210 within the housing. This furthereases the job of the installation engineer, and hence these measurestend to reduce the time taken to install and commission a new system.

As mentioned earlier, the use of a single sheet of metallic material toform the side walls of the main enclosure portion 200 helps to reducethe emissions from the housing. In addition, since this arrangementreduces the number of parts required to construct the housing, theactual cost for producing the housing is reduced. The main enclosureportion can be formed from three main parts, namely the single, shapedsheet of conductive material forming the side walls of the mainenclosure portion 200, a base portion to which the side walls arefastened, and a top cover attached to the upper edge of the side walls.Preferably, the base portion and top cover are riveted to the side wallsand then tack welded to ensure electrical continuity. As mentionedearlier, the generally U-shaped sheets 250 are then added to increasethe structural rigidity of the housing, and to define the wiring portionused for routing the wires.

As shown in FIGS. 2 to 4, in preferred embodiments one side wall of thewiring portion 205 is provided by the sheet 250, whilst the other sidewall of the wiring portion is provided by an edge of the rack. However,in those areas of the housing where a rack has not been attached to thehousing, a blank insert is preferably inserted into the housing, and anedge of the blank insert is used to define a second side wall of thewiring portion 205.

It will be appreciated by those skilled in the art that a housing asdescribed above may be used to retain a plurality of racks for anynumber of different purposes. However, one particular embodiment inwhich the housing may be used is to retain a number of racks which, incombination, form a central terminal of a wireless telecommunicationssystem. Such a wireless telecommunications system may be based onproviding fixed radio links between subscriber terminals at fixedlocations within a service area and the central terminal for thatservice area. The central terminal then typically interfaces with apublic switch telephone network (PSTN) so that calls can take placebetween the PSTN and items of telecommunications equipment connected tothe subscriber terminals.

FIG. 5 is a schematic illustration of a central terminal for such awireless telecommunications system, which is formed by a number of racksinserted into a housing in accordance with preferred embodiments of thepresent invention. The central terminal consists of a number ofequipment racks, including an RF combiner and power amp rack 420, whichalso contains a power supply 425, and a number of (in this example two)modem shelves 410. The RF combiner shelf 420 allows the modem shelves410 to operate in parallel. If "n" modem shelves are provided, then theRF combiner shelf 420 combines and amplifies the power of "n" transmitsignals, each transmit signal being from a respective one of the "n"modem shelves, and amplifies and splits received signals "n" ways sothat separate signals may be passed to the respective modem shelves. Thepower supply 425 provides a connection to the local power supply andfusing for the various components in the housing 200.

In accordance with preferred embodiments, a bidirectional connectionextends between the RF combiner shelf 420 and a central terminalantenna, such as an omnidirectional antenna mounted on a centralterminal mast, this antenna enabling the central terminal to communicatewith the subscriber terminals of the service area. Preferably, thisbidirectional connection enters the housing through the top cover of thehousing.

In preferred embodiments of the present invention, baseband cables forcarrying the signals between the RF Combiner shelf 420 and the modemshelves 410, and the necessary power cables to each of the modemshelves, are passed down the inside of one of the walls forming the mainenclosure portion 200. Since these cables are entirely internal to thehousing, it can be easier to preinstall these in the housing rather thanrouting them via the separate wiring portion, although it will beappreciated by those skilled in the art that this latter approach couldalso be taken. If these cables are passed down the inside of one of thewalls of the main enclosure portion 200, it is especially important tomake sure that they are well screened to minimise noise emitted fromthem.

However, the central terminal also includes a number of coaxial cablesused to route signals between the modem shelves 410 and the PSTNexchange, each such coaxial cable generally being referred to as an E1connection. As the number of users of telecommunications networksincreases, there is an ever increasing demand for such networks to beable to support more users. To increase the number of users that may besupported by a single central terminal, the wireless telecommunicationssystem can be arranged to operate in a Demand Assignment mode, in whicha larger number of subscriber terminals are associated with the centralterminal than can be managed via the wireless links between the centralterminal and the subscriber terminals at any one moment in time. Thewireless links are then assigned to particular subscriber terminals ondemand as needed. All of these subscriber terminals require a point ofpresence at the PSTN exchange, and this increases the number of E1connections that need to be provided between the central terminal andthe PSTN.

Hence, there can potentially be a large number of coaxial cables thatneed to be routed to the modem shelves 410 within the housing 200. Allof these coaxial cables may propagate noise along the outer shieldinglayer of the cables, and hence, without the use of the techniquesdescribed in relation to the housing of the preferred embodiment of thepresent invention, much of that noise would be propagated onto theequipment racks 210, and hence possibly adversely effect the operationof the components on those racks. However, in accordance with preferredembodiments of the present invention, all of these coaxial cables arerouted along the wiring portion 205 and then enter the main enclosureportion 200 at the appropriate level via a bulkhead connector 230, whichearths the outer shielding layer of the coaxial cable to the conductivewall of the main enclosure portion 200, thereby inhibiting thetransmission of noise along those cables to the rack.

As illustrated in FIG. 5, in those portions of the housing 200 where anequipment rack is not present, blank inserts 430 are provided, and anedge of these blank inserts is used to define a second side wall of thewiring portions 205.

FIG. 5 shows a front elevation of the housing, with the wiring portioncovers 260 attached in place to protect the cables from damage duringnormal use. These covers 260 are readily removed, to enable access tothe wiring portions from the front of the housing, thereby easilyenabling new cables to be inserted, and/or cables already in position tobe checked and maintained.

Although a particular embodiment has been described herein, it will beappreciated that the invention is not limited thereto and that manymodifications and additions thereto may be made within the scope of theinvention. For example, various combinations of the features of thefollowing dependent claims could be made with the features of theindependent claims without departing from the scope of the presentinvention.

What is claimed is:
 1. A housing for holding a rack of equipment,comprising:a main enclosure portion for retaining the rack, the mainenclosure portion having a first opening for receiving the rack andcomprising a first wall defining at least one edge of said firstopening; a wiring portion, distinct from said main enclosure portion,for receiving wires to be routed to said rack; the first wall beingarranged to separate the wiring portion from said main enclosureportion, and the wiring portion being located between the first wall anda front face of the housing.
 2. A housing as claimed in claim 1, whereinthe wiring portion has a second opening for inserting said wires in tothe wiring portion, the first opening and second opening beingaccessible from the front face of the housing.
 3. A housing as claimedin claim 1, wherein the wires are routed through said first wall to saidrack.
 4. A housing as claimed in claim 3, wherein each said wireconsists of two separate wires, the first wire being located within thewiring portion, the second wire being located within the main enclosureportion, and the first and second wires being electrically connected toeach other by a bulkhead connector attached to the first wall.
 5. Ahousing as claimed in claim 4, wherein a part of the first wallcomprises a mounting plate formed on the rack, and the bulkheadconnector is attached to said mounting plate.
 6. A housing as claimed inclaim 1, wherein the wiring portion is connected to said first wall. 7.A housing as claimed in claim 1, wherein a back wall of said wiringportion is provided adjacent said first wall, and a first side wall ofthe wiring portion depends from the main enclosure portion.
 8. A housingas claimed in claim 7, wherein a second side wall of the wiring portionis formed by an edge of the rack.
 9. A housing as claimed in claim 8,wherein the second side wall is formed by an edge of a blank insertinserted in to areas of the housing not occupied by said rack.
 10. Ahousing as claimed in claim 1, further comprising a plurality of wallsarranged to define said main enclosure portion, at least two of saidwalls being formed from a single piece of conductive material.
 11. Ahousing as claimed in claim 10, wherein said plurality of walls areformed from a single piece of conductive material.
 12. A housing asclaimed in claim 2, further comprising a cover for said second openingattachable to said wiring portion.